Landsat MMS imagery of a Lower Cretaceous regional dyke swarm, Damaraland, Namibia: a precursor to the splitting of the Western Gondwana.

J Lord, Grahame John Henderson Oliver, J Soulsby

Research output: Contribution to journalArticlepeer-review

12 Citations (Scopus)

Abstract

The visual analysis of digitally-enhanced Landsat Multispectral Scanner (MSS) imagery, covering the western portion of the Central Zone of the Damara Orogen, Namibia, provides an effective and low-cost means of mapping a north-northeast-trending regional dyke swarm. K-Ar dating indicates that these dolerite dykes are Lower Cretaceous (similar to 135 Ma) in age, and represent an intermediate phase of Karoo volcanic activity. The synoptic view afforded by the Landsat imagery allows the spatial outcrop of the dykes to be mapped across a large area, and the dykes prove to be easily reconciled from the spatial component of the imagery because they form dark, positive topographic lineaments, with associated areas of shadowing, set against a, lighter-coloured, flatter, sandy background. A digitally processed dyke-lineament map reveals a strong north-northeast trend, which is broadly parallel to the contemporaneous Southern Atlantic rift, originally located immediately to the west. The dykes were erupted immediately prior to the splitting of Western Gondwana and the formation of the Southern Atlantic Ocean, and are associated with the initial continental rifting processes. Many dykes may have acted as feeders to the flood basalts which were subsequently erupted over much of the area. It is suggested that the emplacement of this regional dyke swarm may represent the latest activity along an earlier crustal weakness.

Original languageEnglish
Pages (from-to)2945-2954
Number of pages10
JournalInternational Journal of Remote Sensing
Volume17
Publication statusPublished - Oct 1996

Keywords

  • SOUTH-ATLANTIC

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